The present invention relates to a composition, in particular a cosmetic composition, with transfer resistance, long wearing, and waterproof properties. The composition comprises, in particular, di-block, tri-block, multi-block and/or radial or star block copolymers. It also relates to cosmetic and pharmaceutical products containing this composition.
Many cosmetic compositions including pigmented cosmetics such as foundations, concealers, mascaras, lipsticks, and other cosmetic and sunscreen lotions leave soft oily films that can transfer quite easily. This means that the composition is capable of becoming deposited, at least in part, on certain supports with which it is brought into contact, such as, for example, a glass, a cup, an item of clothing or the skin. On becoming deposited, the composition leaves a mark on the support. The result is less than optimal persistence of the composition and it requires application to be repeated regularly.
There are several transfer resistant cosmetic compositions that are known in the art; however, the majority of these compositions can still be improved. So-called xe2x80x9ctransfer-freexe2x80x9d make-up compositions known in the art generally comprise, among their constituent fatty substances, volatile oils, in particular volatile silicone oils and/or volatile hydrocarbon oils. Additionally, the majority of these transfer free compositions is tacky; thus, the application and spreadability of the compositions could still be improved.
For example, one reason for poor film formation is that a xe2x80x9ctransfer-freexe2x80x9d make-up composition can require the use of a complex composition in which the oils are partially replaced by volatile solvents which evaporate on contact with the skin, leaving a layer composed essentially of waxes and/or resins, pigments, fillers and actives. Apart from the preparation difficulties associated with the use of volatile compounds, this solution can have the drawback of leading to a make-up effect of powdery and matte appearance.
Another problem that can be encountered with transfer free compositions is stability. Many film formers used in the art need to be gelled in a solvent in order to functions as a thickener. The resulting formulations can present a problem if the solvent in these gel thickeners tends to migrate out of the gel matrix causing instability of the formulation. The need therefore remains for a stable cosmetic composition which transfers little or not at all, that is to say a xe2x80x9ctransfer freexe2x80x9d or transfer resistant composition which also possesses good cosmetic properties such as ease of application, comfort, ease of make-up removal, non greasy, non tacky, non draggy during and after application, and water resistance.
The present invention is a composition which can overcome these disadvantages and obtain a film having properties such as a very good adherence to the substrate, flexibility, wearability, good dry time, non tacky, good retention, non transfer, and low migration overtime. Film formation occurs when the solvent evaporates at a rate that preferably allows the film to form continuously and free from imperfections. The composition of the present invention also has cosmetic properties which can be improved in relation to those of the xe2x80x9ctransfer freexe2x80x9d products of the prior art.
The present invention relates to a transfer resistant composition comprising (a) an effective amount of at least one of a di-block, tri-block, multi-block and/or radial or star block copolymer film former. The composition may further comprise (b) an additional film former or a mixture of additional film formers. The composition may comprise any one of a di-block, tri-block, multi-block or radial or star block copolymer film former or any mixture or blend of co-polymer film formers. A preferred embodiment is a composition comprising a tri-block or a radial or star copolymer film former or a mixture thereof. This preferred embodiment may also comprise an additional film former or a mixture of additional film formers.
In a another preferred embodiment, the transfer resistant composition may comprise an effective amount of at least one copolymer film former selected from di-block, tri-block, multi-block, and radial or star copolymers, and at least one additional film former with the proviso that the additional film former is not selected from alkyl cycloalkylacrylate.
The transfer resistant compositions of the invention may be used in a variety of cosmetic and pharmaceutical products. An effective amount of di-block, tri-block, multi-block and/or radial or star block copolymer film former or additional film former in a cosmetic or pharmaceutical product is the amount necessary to obtain the desired degree of transfer resistance properties. One of skill in the art will be able to determine routinely the effective amount of block copolymer film former and additional film former depending on the application and the transfer resistance properties desired. One of skill in the art will also be able to determine routinely the amount of block copolymer film former, additional film former, and other ingredients needed to obtain a stable cosmetic or pharmaceutical product, depending on the application. A stable cosmetic or pharmaceutical product is one of sufficient stability to enable effective commercialization of the cosmetic or pharmaceutical product.
By way of background, suspending and thickening agents typically include waxes, silica gels, gums, clays, fumed silica, fatty acid soaps, and various hydrocarbon gels. Hydrocarbon gels comprising di-block, tri-block, multi-block and/or radial or star block copolymers are used in the art as gelling agents or suspending and dispersing agents. See U.S. Pat. No.5,756,082, WO 98/42298, and EP 0 497 144 B1, the disclosures of which are hereby incorporated by reference. Copolymers of this type are known in the art to have advantageous properties when used as a suspension agent for various solids and liquids. See WO 98/38981, the disclosure of which is hereby incorporated by reference.
In a preferred embodiment, the di-block, tri-block, multi-block and/or radial or star block copolymer film formers used in the invention contain at least two thermodynamically incompatible segments. A di-block is usually defined as A-B type or a hard segment (A) followed by a soft segment (B) in sequence. A tri-block is usually defined as a A-B-A type copolymer or a ratio of one hard, one soft, and one hard segment. Multiblock or radial or star copolymer film formers usually contain any combination of hard and soft segments, provided that there are both hard and soft characteristics. An example of a hard block copolymer segment is styrene, while examples of soft block copolymer segments are ethylene, propylene, and butylene or combinations thereof.
In another preferred embodiment, the copolymer film former of the present invention is chosen from the class of Kraton(copyright) rubbers (Shell Chemical Company) or from similar gelling agents. In a further preferred embodiment, the copolymer film former comprises Kraton(copyright) rubbers that are present in a gel in amounts from about 10 to about 20% concentration by weight. Kraton(copyright) rubbers are thermoplastic elastomers in which the polymer chains comprise a tri-block, di-block, or radial or star block configuration or numerous mixtures thereof. The Kraton(copyright) tri-block rubbers have polystyrene segments on each end of a rubber segment, while the Kraton(copyright) di-block rubbers have a polystyrene segment attached to a rubber segment. The Kraton(copyright) radial or star configuration, in a further preferred embodiment, may be a four-point or other multipoint star made of rubber with a polystyrene segment attached to each end of a rubber segment. The configuration of each of the Kraton(copyright) rubbers form separate polystyrene and rubber domains.
Each molecule of Kraton(copyright) rubber is said to comprise block segments of styrene monomer units and rubber monomer and/or co-monomer units. The most common structure for the Kraton(copyright) triblock copolymer is the linear A-B-A block type styrene-butadiene-styrene, styrene-isoprene-styrene, or styrene-ethylenebutylene-styrene. The Kraton(copyright) di-block is preferably the AB block type such as styrene-ethylenepropylene, styrene-ethylenebutylene, styrene-butadiene, or styrene-isoprene. The Kraton(copyright) rubber configuration is well known in the art and any block copolymer film former with a similar configuration is within the practice of the invention.
Other preferred embodiments include the use of block copolymer film formers comprising a styrene/butylene/ethylene/styrene copolymer (tri-block), an ethylene/ propylene/styrene copolymer (radial or star block) or a mixture or blend of the two. (Some manufacturers refer to block copolymers as hydrogenated block copolymers, e.g. hydrogenated styrene/butylene/ethylene/styrene copolymer (tri-block) or hydrogenated ethylene/propylene/styrene copolymer (radial or star block), all of which are within the scope of the invention.) Specific examples include Versagel M5960, or Versagel M5970, all of which are available from Penreco of Houston Tex. and block copolymers available from Brooks Industries, such as Gel Base.
The block copolymer film former may preferably be formulated by dissolving the block copolymer in a hydrocarbon solvent. Hydrocarbons useful in the practice of the invention include but are not limited to mineral oils, mineral solvents, mineral spirits, petroleum, waxes, synthetic hydrocarbons, animal oils, vegetable oils, and mixtures of various hydrogen carbons. In a preferred embodiment, the block copolymer film former is formulated by dissolving the block copolymer in isododecane or a light paraffinic solvent. In another preferred embodiment, the block copolymer film former may be formulated by dissolving the block copolymer in a non-hydrocarbon solvent such as amyl acetate, butyl acetate, isobutyl acetate, ethyl acetate, propyl acetate or isopropyl acetate.
The solvent and solubility conditions for formulating a block copolymer film former from a block copolymer will be chosen by a person skilled in the art in order to prepare a composition which has the desired properties. One of ordinary skill in the art will be able to determine the solubility parameters and choose a solvent based on the block copolymer chosen for the envisaged application. More information regarding solubility parameters and solvents useful in the processing of specific block copolymers is available from the various manufacturers of block copolymers, e.g. Shell Chemical Company. Additional discussions of polymer solubility parameter concepts are presented in: Encyclopedia of Polymer Science and Technology, Vol. 3, Interscience, New York (1965) and Encyclopedia of Chemical Technology, Supp. Vol., Interscience, New York (1971), the disclosures of which are hereby incorporated by reference.
Preferably, the block copolymer film formers of the present invention are water insoluble, can be processed at room temperature, offer excellent adherence to the skin, and are tack free. It is preferred that the copolymer film former be present in the outer phase of any cosmetic formulation and at high concentrations. Additionally, it is preferred that the copolymer film former be compatible with the other raw materials of that phase.
In another preferred embodiment, the block copolymer film former may be combined in a formulation with an additional film former (b). This additional film former may improve smoothness or spreadability, water-resistance, transfer resistance properties, or other cosmetic or pharmaceutical properties desired by one of skill in the art.
Depending on the application, the concentration of block copolymer film former may vary considerably. One of skill in the art will be able to determine routinely the preferred concentration of block copolymer film former depending on the application and the transfer resistance properties desired. For example, for cosmetic foundations, the block copolymer film former or block copolymer film former mixtures may preferably be used in an amount from less than about 1% to about 30% by weight, and more preferably from about 1% to about 15% by weight. For eyeliner formulations, the block copolymer film former or block copolymer film former mixture preferably may vary from about 5% to about 70% by weight, and more preferably from about 20% to about 70% by weight. For lipstick formulations, the block copolymer film former or block copolymer film former mixture preferably may vary from about 1% to about 70% by weight, and more preferably from about 10% to about 70% by weight.
The preferred concentration of additional film formers may also be determined by one of skill in the art and can vary considerably based on the application. For example, for cosmetic emulsions, an additional film former or combination of additional film formers is preferably used in an amount from less than 1% to 15% by weight, and more preferably from 1% to 10% by weight. For eyeliner formulations, the additional film former or combination of additional film formers are preferably used in an amount from less than 0.5% to 15% by weight, more preferably from 1% to 10% by weight. For lipstick formulations, the additional film former or combination of additional film formers is preferably used in an amount from less than 0.5% to 15% by weight, more preferably from 1% to 10% by weight.